RU2566840C1 - Production of glass-ceramic material of cordierite composition - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: claimed process comprises the grinding of glass ceramic of magnesium-silica-alumina composition in wet process to production of aqueous slip. Blanks are made of porous shapes and heat treated at the temperature increase and decrease rate of not over 500°C/h. At grinding step, the dispersing agent is added as a sodium salt of polyacrylic acid in the amount of 1.6-2.0% of loaded dispersion medium. Glass is ground to water slip of density ρ = 2.06-2.20 g/cm³, pH = 8.0-9.5 and fineness with residue on screen of 0.063 mm T₆₃ = 6-12%.

EFFECT: dense sintered glass ceramic of cordierite composition.

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Description

The invention relates to the production of highly heat-resistant radiolucent ceramic materials in an alkali-free magnesium aluminum silicate system used in radio engineering products.

A known method of producing products from a sintered glass crystalline material of lithium aluminum silicate composition (RF Patent No. 2222505, IPC С03С 10/12, January 27, 2004), including grinding pre-crystallized glass by a wet method to obtain an aqueous slip, molding the products into porous forms and their heat treatment during a temperature of 1210-1250 ° C for 1-3 hours at a rate of rise and decrease in temperature of 500 ° C per hour.

Due to the fact that the method is intended to produce a glass-crystalline material of a lithium aluminum silicate composition, it is not suitable for obtaining a dense sintered material of a cordierite composition, since magnesium oxide MgO contained in the cordierite system is partially soluble in a dispersion medium (water), and to obtain a slip with the required casting parameters require a large amount of water, resulting in low-strength, highly porous castings.

The objective of the present invention is to increase the density and decrease the porosity of castings in order to obtain high-density sintered material cordierite composition.

This object is achieved by the fact that the proposed method of manufacturing a glass-ceramic material of cordierite composition, including grinding the crystallized glass of magnesium-aluminum-silicate composition by wet method to obtain an aqueous slurry, forming blanks into porous forms and their heat treatment at a rate of rise and decrease in temperature of not higher than 500 ° C per hour, differing the fact that at the grinding stage, a dispersant in the form of the sodium salt of polyacrylic acid is introduced into the dispersion medium (distilled water) stve 1.6-2.0% of the loaded volume of water, and grinding the crystallized glass is performed to obtain an aqueous slurry density ρ = 2,06-2,20 g / ^cm3, pH = 8,0-9,5 and a fineness the sieve residue is 0.063 mm T ₆₃ = 6-12%.

The authors experimentally established that the introduction of the dispersant in the form of the sodium salt of polyacrylic acid in the stated ratio at the grinding stage is necessary to obtain a suspension with the required casting parameters, which ultimately provides a dense sintered material.

It was experimentally established that grinding crystallized glass of a magnesium aluminum silicate composition, including the introduction of a dispersant in the form of the sodium salt of polyacrylic acid, should be performed in a ball mill to obtain a slip with the following casting characteristics: density ρ = 2.06-2.20 g / cm ³ , pH 8 , 0-9.5 and fineness with a sieve residue of 0.063 mm T ₆₃ = 6-12%. Going beyond the specified parameters of the slip leads to an increase in porosity of the casting up to 35%, which makes it practically impossible to sinter castings to a high density.

The implementation of the proposed method is presented in the following examples.

Example 1

The starting material used was granulate of magnesium aluminum silicate glass of the following chemical composition: MgO - 11.8%; Al ₂ O ₃ - 29.8%; SiO ₂ - 45.9%; TiO ₂ - 12.0%; As ₂ O ₅ - 1.85%, crystallized by two-stage heat treatment at a temperature of the first stage of 850 ° C and holding for 3 hours, then at a temperature of the second stage of 1230 ° C and holding for 4 hours. As the main phases, the obtained material contained indialite (cordierite system), rutile, a small amount of cristobalite, traces of enstatite.

For grinding, the feedstock and grinding media from Al ₂ O ₃ in a ratio of 1: 4 were loaded into the mill, distilled water was introduced with a dispersant in the form of sodium salt of polyacrylic acid in the amount of 1.6% of the amount of water loaded, and wet grinding was carried out for 9- 11 o'clock. Stabilization was carried out by mechanical stirring for 17-25 hours. The resulting slip had the following parameters: density ρ = 2.125 g / cm ³ ; pH = 8.90; fineness with a sieve residue of 0.063 mm T ₆₃ = 11.84%.

From the obtained slurry, plates in the form of plates were molded into plaster molds and heat treatment was carried out in air at a temperature of 1375 ° C with a rate of rise and decrease in temperature not exceeding 500 ° C for 5 hours.

Example 2

The example according to example 1, characterized in that the introduction of the sodium salt of polyacrylic acid is carried out in an amount of 1.8% of the volume of the loaded dispersion medium.

Example 3

The example according to example 1, characterized in that the introduction of the sodium salt of polyacrylic acid is carried out in an amount of 2.0% of the volume of the loaded dispersion medium.

The level of properties of raw castings and glass-ceramic material obtained in example 1, 2 and 3, are presented in table 1.

The presented data show that the proposed technical solution allows to obtain castings with a density of more than 2.00 g / cm ³ and porosity of not higher than 25%, which ensures the production of dense sintered glass-ceramic material with a density of up to 2.60 g / cm ³ and porosity of not more than 0.06 %

Information sources

1. RF patent No. 2222505, IPC С03С 10/12, 01/27/2004, Bull. Number 3.

Claims (1)

A method of manufacturing a glass-ceramic material of cordierite composition, including wet grinding of crystallized glass to obtain an aqueous slurry, forming blanks into porous forms and heat treatment with a rate of rise and decrease in temperature of not higher than 500 ° C per hour, characterized in that a dispersant is introduced into the grinding stage in the form of sodium salt of polyacrylic acid in an amount of 1.6-2.0% of the volume of the loaded dispersion medium, and the glass is crushed to obtain an aqueous slip tightly Tew ρ = 2,06-2,20 g / ^cm3, pH = 8,0-9,5 and a fineness residue on sieve with 0.063 mm T = ₆₃ 6-12%.